关键词: 雷暴, 气候特征, 小波分析, 环流背景, 岢岚

Abstract:

Based on the hourly thunderstorm observation data in Kelan of Shanxi and NCEP reanalysis data during 1970-2014, the climate characteristics of thunderstorms were analyzed statistically by using linear tendency estimation, Morlet wavelet analysis and Mann-Kendall test, the characteristics of mean atmospheric circulation and convective stability from June to August in the years with severe thunderstorms during 1970-2014 were discussed by using composite analysis. The results are as follows: (1) The seasonal and time characteristics of thunderstorm in Kelan of Shanxi were very obvious during 1970-2014, the thunderstorm mainly occurred from June to August, which accounted for about 74.08% of the total, and it mainly occurred from 13:00 to 21:00, which accounted for about 66.46%. The annual thunderstorm days presented an increasing trend on the whole in the past 45 years, and the climatic tendency rate was 1.8 d·(10 a)-1. The initial date of thunderstorm in Kelan was 25 March, while the ending date of thunderstorm was 3 November, and the annual variations of the initial and ending dates of thunderstorm were great during 1970-2014. (2) The significant periods of thunderstorm days during 1970-2014 were 2.4570 a and 4.1322 a. (3) On 500 hPa geopotential height and anomaly fields, the Kelan of Shanxi located at the bottom of trough in active thunderstorm years, while it located in the northwest airflow behind the trough in less active thunderstorm years. (4) The value of CAPE was 229.701 J·kg-1 in active thunderstorm years, and it was 2.0191 times of that in less active thunderstorm years, and the value of K-index in active thunderstorm years was 31.5934 ℃, and it was lightly larger than that in less active thunderstorm years, which indicated that the atmosphere was more unstable in active thunderstorm years.

Key words: thunderstorm, climate characteristics, wavelet analysis, circulation background, Kelan